PREHEAT oven to 375°F. Beat butter, brown sugar, granulated sugar, vanilla and eggs in large bowl with electric mixer on medium speed until light and fluffy. Add flour and baking soda; mix well. Stir in oats and chopped chocolate.
DROP 1/3 cupfuls of dough, 3 inches apart, onto ungreased baking sheet. Shape each into a 1/2-inch-thick heart, using floured hands.
BAKE 14 min. or until lightly browned. Remove to wire racks; cool completely.